Crew members are replaced by aliens in a strange way.
The crew of Voyager is mysteriously replaced, one at a time, by aliens who are transported onto the ship while the crew members are taken to an unknown location. The remaining officers struggle to understand what is happening as the ship is taken over.
The episode is a science-fiction puzzle that builds slowly and adds to the sense of unease. It also asks viewers to consider the situation from the aliens' point of view, as they too are in a strange place and are just as frightened as the crew. It is a tense piece with a clever resolution.